The Court of Appeal has ordered a retrial for Chris Messer, a Saint John Police offer, who had been found guilty of assault in 2012. (Facebook)

The New Brunswick Court of Appeal has struck down the conviction of a Saint John police officer found guilty last year of assault and making threats.

The province’s top court called the trial judge's decision against Christopher Robert Messer last August "unreliable" and ordered a retrial on the charge of assault.

The constable was sentenced to three months in jail for harassment and assault against two people he suspected of breaking into at his home.

He was released a week after his conviction, pending his appeal.

The Court of Appeal ruled on Thursday the trial judge at the Court of Queen's Bench did not clearly outline the reasons for the verdict and offered "much editorial commentary"... setting out different versions of events from testimonies at trial.

"What we do not know is why the trial judge, applying proper credibility findings, arrived at this particular conclusion. As the attorney general points out, the reasons for decision are unreliable and do not lend themselves to meaningful appellate scrutiny. For this reason, the proper course is to set aside the conviction and order a new trial," the Court of Appeal's decision said.

Messer will be retried in front of a judge and jury.

The original charges stem from complaints by two people Messer suspected of being involved in the break-in at his home on Westfield Road.

In the trial, the court heard Messer sent a work email, asking his fellow officers to find out what they could through sources.

Later that day, Messer was alerted by colleagues that they had pulled over a vehicle matching that description in the parking lot of Canadian Tire. One of the complainants, Brett McAdam, was inside and Messer went to the scene.

McAdam testified that after being asked to sit in Messer's cruiser, the officer drove it around the back of the store where he yelled accusations, threatened to blow McAdam's head off, cut it off with a butcher knife, and send "lowlife scum" to his home.

Two weeks after that, the second complainant, Randy King, who was wanted on an arrest warrant, was stopped by police.

King told the court in 2012 that Messer punched him in the head up to 10 times and then put his boot on King's throat.